Can't see it remotely.
Both cars weigh almost exactly 4000lb.
The GC has puts out 245hp from its 5.9 litre V8, and 335 lb/ft torque. It does 0-60 in 7.3 seconds. That's 41 bhp / litre. It has a 4 speed auto.
The M5 puts out 507 hp from its V10 engine, and 383 lb/ft torque. It does 0-62 in 4.7 seconds. That's 100 bhp / litre. It has a 7 speed auto. De-retricted, it will reputedly do almost 205 mph
Dave Milne, Scotland '91 Grand Wagoneer, '99 TJ